Acts 2:42
and they stedfastly continued in the teaching of the apostles, and in the fellowship, in the breaking of the bread, and in the prayers.
1 Corinthians 15:33-34
Do not deceive yourselves. Evil companions ruin good morals.
2 Corinthians 6:14-18
Be not unequally yoked with unbelievers; for what fellowship has righteousness with lawlessness? what communion has light with darkness?
Hebrews 10:24
and let us consider one another, to provoke unto love and good works;
Revelation 18:4
And behold I heard another voice from heaven saying. "Come out of her, that you have no fellowship with her sins, And that you receive not her plagues.